Abstract:

With environmental concerns, alternative solutions for generating electricity while decreasing the consumption of fossil fuels have gained a great importance. Polygeneration is one of these solutions which is also capable to increase the technical performance of electricity generation. Polygeneration systems are available in large scale, medium scale and small scale. This study focuses on small scale polygeneration systems specifically for residential applications. Type and size of the components and the system’s operational strategy plays a significant role in polygeneration system design as these factors affect the system cost and also environmental impacts. This study aims to propose a guide for component selection, sizing and addressing a suitable operational strategy for a predefined system configuration.

Decision making criteria is defined for component selection by a comprehensive literature review. Internal combustion engines, Stirling engines, micro gas turbines and fuel cells are investigated within these criteria. This provides the user an insight on component selection. When combined with factors such as market conditions, location and especially household demand profile, a selection can easily be made by the customer. For component sizing and operational strategy, a model has been implemented in Matlab. A baseline case model with a predefined system configuration and operational strategy was defined. The baseline case system includes a prime mover, a back-up auxiliary boiler, a vapor compression refrigeration chiller, a thermal energy storage and solar thermal collectors for the domestic hot water demand. The operational strategy is defined as thermal load following. For the case study, this model was altered for different cases with alterations on the operational strategy and the system configuration in order to identify the optimal solution for the user where the total annual cost is minimized while satisfying all kinds of end-use demands of a single-family household in Ankara, Turkey. The results also give insights on the effect of having solar thermal collectors and a thermal energy storage coupled with a CHP unit on the overall system.